243 lines
7.3 KiB
C
243 lines
7.3 KiB
C
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/*
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* Copyright (c) 2006-2022, RT-Thread Development Team
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Change Logs:
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* Date Author Notes
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* 2019-10-12 Jesven first version
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* 2022-11-14 WangXiaoyao Optimize footprint and performance
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* Export as ADT for generic use case
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*/
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#include <stddef.h>
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#include <stdint.h>
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#include "avl.h"
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#define HEIGHT_OF(node) ((node) ? (node)->height : 0)
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#define IS_RCHILD(node) (!((node) - ((node)->parent->avl_right)))
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#define IS_LCHILD(node) (!((node) - ((node)->parent->avl_left)))
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#define NODE_PLACE(node) \
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IS_LCHILD(node) ? &(node)->parent->avl_left : &(node)->parent->avl_right
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static inline void rotate_right(struct util_avl_struct *axis,
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struct util_avl_struct *lchild,
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struct util_avl_struct *lrchild,
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struct util_avl_struct **nodeplace,
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size_t lrheight)
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{
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axis->avl_left = lrchild;
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lchild->avl_right = axis;
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axis->height = lrheight + 1;
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lchild->height = axis->height + 1;
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lchild->parent = axis->parent;
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axis->parent = lchild;
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*nodeplace = lchild;
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if (lrchild != NULL)
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lrchild->parent = axis;
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}
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static inline void midmount_right(struct util_avl_struct *axis,
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struct util_avl_struct *lchild,
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struct util_avl_struct *lrchild,
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struct util_avl_struct **nodeplace,
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size_t lrheight)
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{
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lchild->avl_right = lrchild->avl_left;
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axis->avl_left = lrchild->avl_right;
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lrchild->avl_left = lchild;
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lrchild->avl_right = axis;
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lrchild->height = lchild->height;
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lchild->height = lrheight;
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axis->height = lrheight;
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lrchild->parent = axis->parent;
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lchild->parent = lrchild;
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axis->parent = lrchild;
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if (lchild->avl_right != NULL)
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lchild->avl_right->parent = lchild;
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if (axis->avl_left != NULL)
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axis->avl_left->parent = axis;
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*nodeplace = lrchild;
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}
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static inline void rotate_left(struct util_avl_struct *axis,
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struct util_avl_struct *rchild,
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struct util_avl_struct *rlchild,
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struct util_avl_struct **nodeplace,
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size_t rlheight)
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{
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axis->avl_right = rlchild;
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rchild->avl_left = axis;
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axis->height = rlheight + 1;
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rchild->height = axis->height + 1;
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rchild->parent = axis->parent;
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axis->parent = rchild;
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*nodeplace = rchild;
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if (rlchild != NULL)
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rlchild->parent = axis;
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}
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static inline void midmount_left(struct util_avl_struct *axis,
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struct util_avl_struct *rchild,
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struct util_avl_struct *rlchild,
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struct util_avl_struct **nodeplace,
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size_t rlheight)
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{
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rchild->avl_left = rlchild->avl_right;
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axis->avl_right = rlchild->avl_left;
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rlchild->avl_right = rchild;
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rlchild->avl_left = axis;
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rlchild->height = rchild->height;
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rchild->height = rlheight;
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axis->height = rlheight;
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rlchild->parent = axis->parent;
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rchild->parent = rlchild;
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axis->parent = rlchild;
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if (rchild->avl_left != NULL)
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rchild->avl_left->parent = rchild;
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if (axis->avl_right != NULL)
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axis->avl_right->parent = axis;
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*nodeplace = rlchild;
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}
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/**
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* @brief avl insertion & delete conceptually contain 2 stage
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* 1. insertion/delete of reference
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* 2. rebalance
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*/
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void util_avl_rebalance(struct util_avl_struct *node,
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struct util_avl_root *root)
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{
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if (!node)
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return;
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struct util_avl_struct *axis = node;
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struct util_avl_struct **nodeplace;
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do
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{
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struct util_avl_struct *lchild = axis->avl_left;
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struct util_avl_struct *rchild = axis->avl_right;
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nodeplace = axis->parent ? NODE_PLACE(axis) : &root->root_node;
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int lheight = HEIGHT_OF(lchild);
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int rheight = HEIGHT_OF(rchild);
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if (rheight + 1 < lheight)
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{
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struct util_avl_struct *lrchild = lchild->avl_right;
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size_t lrheight = HEIGHT_OF(lrchild);
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if (HEIGHT_OF(lchild->avl_left) >= lrheight)
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{
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rotate_right(axis, lchild, lrchild, nodeplace, lrheight);
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axis = lchild->parent;
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}
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else
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{
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midmount_right(axis, lchild, lrchild, nodeplace, lrheight);
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axis = lrchild->parent;
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}
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}
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else if (lheight + 1 < rheight)
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{
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struct util_avl_struct *rlchild = rchild->avl_left;
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size_t rlheight = HEIGHT_OF(rlchild);
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if (HEIGHT_OF(rchild->avl_right) >= rlheight)
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{
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rotate_left(axis, rchild, rlchild, nodeplace, rlheight);
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axis = rchild->parent;
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}
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else
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{
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midmount_left(axis, rchild, rlchild, nodeplace, rlheight);
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axis = rlchild->parent;
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}
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}
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else
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{
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int height = (lheight < rheight ? rheight : lheight) + 1;
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if (height == axis->height)
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break;
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axis->height = height;
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axis = axis->parent;
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}
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} while (axis);
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}
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void util_avl_remove(struct util_avl_struct *node, struct util_avl_root *root)
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{
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struct util_avl_struct **nodeplace;
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if (root->root_node == NULL)
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return;
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if (node->parent != NULL)
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{
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nodeplace = NODE_PLACE(node);
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}
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else
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{
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nodeplace = &root->root_node;
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}
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/* deletion */
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if (node->avl_right == NULL)
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{
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*nodeplace = node->avl_left;
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if (node->avl_left != NULL)
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node->avl_left->parent = node->parent;
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node = node->parent;
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}
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else
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{
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struct util_avl_struct *rchild = node->avl_right;
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if (rchild->avl_left == NULL)
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{
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*nodeplace = rchild;
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rchild->avl_left = node->avl_left;
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if (rchild->avl_left != NULL)
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rchild->avl_left->parent = rchild;
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rchild->parent = node->parent;
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util_avl_rebalance(rchild, root);
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node = rchild->parent;
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}
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else
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{
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struct util_avl_struct *successor = rchild->avl_left;
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struct util_avl_struct *sparent = rchild;
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while (successor->avl_left != NULL)
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{
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sparent = successor;
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successor = successor->avl_left;
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}
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*nodeplace = successor;
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sparent->avl_left = successor->avl_right;
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successor->avl_left = node->avl_left;
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successor->avl_right = node->avl_right;
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if (successor->avl_left != NULL)
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successor->avl_left->parent = successor;
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successor->avl_right->parent = successor;
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if (sparent->avl_left != NULL)
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sparent->avl_left->parent = sparent;
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successor->parent = node->parent;
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util_avl_rebalance(sparent, root);
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node = successor;
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}
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}
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/* rebalance */
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util_avl_rebalance(node, root);
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return;
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}
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